Conventional explanations for a country's political system would draw on its history, economy and culture. Randy Thornhill from the University of New Mexico, Albuquerque, however, thinks it might be determined by the threat of disease in a region. This triggers psychological biases, which originally evolved to prevent illness spreading, that also hinder the emergence of democratic ideals. Some support for this idea comes from statistical comparisons of different regions.

An infectious idea Comparing democracy with rates of infection across the world produces an intriguing correlation (based on data from the Global Infectious Diseases and Epidemiology Online Network and figures from Democatization: A comparative analysis o